E150 Transmission not shifting hot weather

The transmission in 1994 E150 van is very slow in changing gears in hot weather (takes 2 or 3 blocks or more). It works fine when the temperature is below 70F or 21C. Easing up on the gas pedal or manually shifting down and then up sometimes helps. If the temperature is in the 90F this trouble is on from a cold start. Often if the temperature is between 80F and 90F it works OK from a cold start but then if I stop such at a red light the trouble is on again. It is embarrassing going 10-20 mph with the engine roaring and traffic is building up behind me. My dealer says he cannot locate the problem unless it is on but as the temperature here is cooler than in the southern states where I go for winter holidays it is working most of the time here in northern Alberta. This trouble has been on for a few years but I would like to get it fixed as I would like to make more trips where it is warmer.

Without watching live data in the vehicles computer system or monitoring signals sent to the transmission from the ECM, all one can do is make an educated guess. You could have a defective TOT (transmission oil Temp) sensor, accumalator valve hanging, MAF (mass air flow) sensor malfunction or low engine power so as you push deeper into the accelerator it makes an upshift later. Those are just a couple things off the top of my head :)

Without watching live data in the vehicles computer system or monitoring signals sent to the transmission from the ECM, all one can do is make an educated guess. You could have a defective TOT (transmission oil Temp) sensor, accumalator valve hanging, MAF (mass air flow) sensor malfunction or low engine power so as you push deeper into the accelerator it makes an upshift later. Those are just a couple things off the top of my head :)
Thanks RexNfx400.
Where is the TOT located? Interneal or external of the transmission?
Thanks
normanrayw

Hi
The TOT is part of the solenoid block. The solenoid block has all the shift solenoids and motors built into one unit. Which is within the Transmission pan. Held on by about 10 bolts.

One other thing. Is to update the MLPS(Manual lever position sensor) some will call it a park/nuetral switch. The Pre-'95s have a tan sensor, which has to be updated to later design black sensor. Many weird problems from the tan sensor. This hooks to the gear select linkage on the side of the transmission. It takes a little wiring knowledge to update this.

Remember, These are quesses based without monitoring computer data.